1. Technical Field
The present disclosure relates to an aligning device for precisely aligning electronic components such as wafers, a bonding apparatus equipped with the aligning device, and an aligning method.
2. Background Art
In a known method for bonding liquid crystal substrates, an upper surface plate, on which an upper substrate having a positioning mark is held, and a lower surface plate, on which a lower substrate similarly having a positioning mark is held, with an elastic material disposed between the upper and lower surface plates, are stored to face each other in a vacuum chamber. The positions of the marks on the upper and lower substrates are recognized, and an absolute difference between the positions is recognized. When it is determined that the absolute difference between the mark positions is not a predetermined value, the lower substrate is moved by a linear driving unit with a correction amount corresponding to the amount of deformation of the elastic material (see the following Patent Document 1).
Further, a vacuum chamber including a movable unit, a fixed member, and a flexible and cylindrical member that is not air-permeable is known. The movable unit includes a sample stage on which a sample is placed, and a driving mechanism for driving the sample stage. The fixed member is provided with equipment for subjecting the sample to predetermined treatment. The cylindrical member is hermetically connected at one end to the fixed member, and is hermetically connected at the other end to the movable unit. The sample stage is placed in an evacuated space that is defined by the movable unit, the fixed member, and the cylindrical member. The driving mechanism is placed outside the space (see the following Patent Document 2).    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-151215    Patent Document 2: Japanese Unexamined Patent Application Publication No. 10-258224
In the above-described Patent Document 1, cameras for finding the positioning marks provided on the upper and lower substrate are mounted below the lower substrate. Therefore, the distance in which the lower surface plate is movable to respond to misalignment is shortened (if the movable distance of the lower surface plate is increased, the lower surface plate comes into contact with recesses in which the cameras are mounted). Moreover, since the elastic material is provided between the lower surface plate and the upper surface plate, it is difficult to precisely recognize both marks.
Since the above-described Patent Document 2 is originally not intended to align and bond two electronic components, it does not disclose an optical system for alignment. If a camera is placed below the sample stage, problems similar to those in the above-described Patent Document 2 arise. Further, it is physically difficult to insert an optical system in a cutout provided in the flexible cylindrical member, because deformation of the cylindrical member imposes load on the optical system.